The Other Earth by Zahir Hasan

When astronomer Dr. Lena Okafor discovers a planet twelve light-years away whose continents, oceans, and cities mirror Earth, the scientific world is stunned. The impossible becomes terrifyingly real when a transmission arrives from the planet — and it knows her name. Soon physicist Daniel Mercer, haunted by his role in the classified Janus experiment, receives a second warning: he must never come to that world. But as governments tighten their grip and the mystery deepens, Lena and Daniel are drawn into a race across science, secrecy, and space itself. On the Other Earth they find a civilization both familiar and unsettlingly different — a world shaped by other choices, other losses, and one revelation powerful enough to threaten both planets. Part first-contact mystery, part high-stakes adventure, The Other Earth is a sweeping novel of suspense, discovery, and the question at the heart of every civilization: if another humanity exists, what do we owe each other?